NEURO-Skeletal Contraction and Dystrophies

Question 1

What is purpose of our muscles?

Answer 1

40% of body, move bones. 1. Only shortens- Antagonist contract/shorten to stretch agonist

Question 2

How are msk packed?

Answer 2

Fascia- skeletal muscle -perimysium -epimysium- fascicle myofibrils: cells contractile proteins bundles into fibers.

Question 3

The membrane of a musle cell is called?

Answer 3

Sarcolemma. Sacroplasmic reticulum stores calcium

Question 4

What are the two long F polymers strands coiled around each other that are attached to z-disk w/in sacromere?

Answer 4

ACTIN- Thin filament

Question 5

This structure is multple protein wraped around actin?What is ontop of this structure? What does it cover

Answer 5

Tropmyosin- cover G-actin active site ADP. Troponin is on top of tropomyosin

Question 6

This structure has two helical proteins composed 6 polypetide chains as a tail with two head groups to as attachment sites?

Answer 6

MYOSIN-THICK

Question 7

How is a fiber innervated?

Answer 7

Contraction begins with a nerve stimulation, 1 nerve does not stimulate all fibers. Paralle stack, not like cardiac. Contracts different fiber diff times

Question 8

Individual nerve fiber and all the muscles that are innervated by it?

Answer 8

motor unit- LARGE groups have fewer motor units, less fine tuning. SMALL group-hand, have more motor units smaller

Question 9

This space is where the neuron sits in the synaptic gutter in the sarclema which is folded w/ ACH receptor?

Answer 9

Neuromuscular juntcion

Question 10

What ion is used to release NT into the synpatic gutter?

Answer 10

Ca

Question 11

What is release in the NMJ and binds to ligand channel gated channel on the motor end plate (aka postsynaptic).

Answer 11

2 ACH create + charge, opens a Na, for influx thus moving potential to Na reveral potential for an AP

Question 12

This AP caused what to happen in the sarcoplasma reticulum?

Answer 12

Release calcium storage- Na cause AP of nerve__Ca influx in nerve cell__vesicles move to synapse to release NT__ACH__ACH bind to post synaptic membrane on MSK___+charge opens Na on MSK membrane__AP d/t reversal potential of Na__cause SR to release calcium___Ca initiates tension/contraction

Question 13

What is made up of tropoin and where are its attachment sites?

Answer 13

3 protein units- Ti- ACTIN, TT-tropomyosin, TC-calcium

Question 14

At rest where is the tropomyosin/tropoin proteins?

Answer 14

Covering G-actin ADP active site on actin

Question 15

What causes myosin head to attach to actin?

Answer 15

NA AP released Ca from SR. Ca binds to TC__ Changes structure pulls tropomyosin off binding site__ATP binds to myosin head__Binding creates Hydrolysis ATP to ADP myosin OPEN state__myosin attaches to G-actin site__ADP get kicked off___another shape change__ pulls actin closer__ATP bind again to kick off myosin__resets

Question 16

What pulls the Z-disk together?

Answer 16

ATP helps Bending of the myosin heads attached on actin. Hydolyis forms ADP+P

Question 17

Why is max force 110% of sacromere length?

Answer 17

Normal resting length is max tension developed.
Shortened/compressed- tension limits force b/c z-disk block by myosin ends.
No cross bridges at myosin center= no force generation Lengthen to far- actin cant bind to myosin

Question 18

What is work?

Answer 18

Load x Distance move. Greater load, greater velocity

Question 19

What is the meaning of life?

Answer 19

Phosphorylation. Creatine from arginine kidney, made in liver. Creatine phosphate stored in muscle. Fast but short lived. 4m/sec

Question 20

What is ideal energy source but long to develop, and last longer bc produce 6xmor ATP?

Answer 20

Oxidative phosphorylatin from food. Glycolysis=INC ATP

Question 21

What are types of tension development?

Answer 21

1. Isometric-Tension=load no change in length.
2. Isotonic- Tension >Load
3. Lengthening= Tension < load, heavy

Question 22

WHat fiber fatigues faster, larger, strong, Large SR, fast ion release, INC enzymes, blood supply reduced, fewer mitochondria?

Answer 22

FAST twitch

Question 23

What fiber less fatigue, more mitochondria, more blood supply, large myoglobin, depends on sugars and oxidatavie phosphy, generate more tension?

Answer 23

Slow twitch

Question 24

What motor units are more excitable?

Answer 24

Spatial summation- space multiple units. Smaller unit contract 1st, but as signal grows large kick in. Smooth movement d/2 alternating various units

Question 25

What is state of sustained contraction over time?

Answer 25

Tetanus- temporal frequency summation. Every moment

Question 26

What occurs during period of rest within sarcoplasmic retiuc that influence strength of contraction?

Answer 26

Stepwise rest periods show inc in Ca with each rest

Question 27

What contriubute to mucle tone at rest?

Answer 27

Slow level of release of Ach from low baseline rate of nerve impulses. Provides bulk via trophic effect. IE Cerebral palsy-tonic contracture protective, UMN

Question 28

What occurs with loss of glycogen storage resulting in loss of strength/tension/contraction?

Answer 28

Fatigue- transmission of nerve also reduced with prolonged stimulation. Less ACH, Less CA, less strength IE. do PE neuro once

Question 29

Muscle apply tension at insertion on bone, this creates what type of system?

Answer 29

Lever system- force related to distance from fulcrum and length of lever arm. If LONG lever arm, close load to fulcrum= less force generation, easy

Question 30

What occurs with muscle hypertrophy?

Answer 30

fibers larger, more enzymes, | new sarcomeres with size of stretch fiber

Question 31

What does muscle atrophy take place?

Answer 31

Fatigue- the more stimulation the more burning thru glyco stores IF lose ACH, lose trophic effect Denervation Starts immediately BUT cannot see til late.

Question 32

What occures with denervation?

Answer 32

Fibers destroyed replaced with fibrous scar or fat. | Neighbors motor units can sprout, but loss dexterity

Question 33

What is characteristic of mixed muscle atrophy, hypertrophy, fiber replaced with scar and fat material, progressive in weakness as MC SX?

Answer 33

Dystrophies >30. 1. Mostly boys. 2Onset 3-5y. 3.Walk on tip toes 4. clumsy. Runs awkward. Fall often. 5. Walks up from seated position. 6. Lordosis

Question 34

This disorder requires dystophin- msk structure, but is inhertibly abscent?

Answer 34

Duchenne MD Onset 3-5yo. Most cant walk by age 12.

Question 35

This disorder is less severe form of dys dystophin

Answer 35

Becker MD

Question 36

This MD slowly progressive disorder of face, arms, shoulder beginning in teen?

Answer 36

Fascioscapulohumeral

Question 37

MC adult form characterized by cardiac abnormalities and cataracts, swan neck (from inability to support the weight of the head), drooping eyelids

Answer 37

Myotonic

Question 38

What is most life threatening of MD?

Answer 38

Heart and breathing muscles get weak- Child usually dies before age 20 from heart failure or pneumonia.